Set-top box including a single tuner for video and data over cable

Abstract

A cable network includes a cable modem termination system at the head end of a cable network, which transmits digitized video data and digitized data, according to a Data Over Cable System Interface Standard (DOCSIS), from sources external to the cable network downstream to a cable subscriber's set-top box over a selected downstream channel. The set-top box includes a single downstream tuner for selecting the digitized video data and DOCSIS data over the selected downstream channel.

1 . A cable network comprising: 
 a head end that receives digitized data and a plurality of digitized video channels from external sources;    a cable modem termination system that converts the digitized data according to a Data Over Cable System Interface Standard (DOCSIS) to produce a DOCSIS digitized data channel for transmission over a downstream channel;    a multiplexer that multiplexes the DOCSIS digitized data channel with the plurality of digitized video channels to form a plurality of downstream output channels, each of the plurality of downstream output channels including DOCSIS broadcast data and a filtered selection of unicast data; and    a set-top box that includes a single downstream tuner, the single downstream tuner selecting one of the plurality of downstream output channels comprising the filtered selection of unicast data, the DOCSIS broadcast data, and one of the corresponding plurality of digitized video channels.    
   
   
       2 . The cable network of  claim 1 , wherein the DOCSIS digitized data channel comprises a plurality of DOCSIS digitized data channels.  
   
   
       3 . The cable network of  claim 2  further comprising: 
 a DOCSIS modem that demodulates the DOCSIS digitized data channel when the single tuner selects the one of the plurality of downstream output channels and that modulates upstream digital data to the head end of the cable network on an upstream band.    
   
   
       4 . The cable network of  claim 1 , wherein the plurality of digitized video channels are formatted to an MPEG format and are multiplexed with the DOCSIS digitized data channel according to a time division multiple access protocol to form an MPEG transport stream for downstream transmission.  
   
   
       5 . The cable network of  claim 3  further comprising: 
 a video processor that receives the one of the correspond plurality of digitized video channels from the demodulator of the DOCSIS modem, when the single downstream tuner selects the one of the plurality of downstream output channels, the video processor including a video decoder that decodes MPEG format.    
   
   
       6 . The cable network of  claim 2 , wherein an output of the cable modem termination system (CMTS) is filtered, according to unicast data, by one of a plurality of filters to produce filtered data for a corresponding one of the plurality of downstream output channels corresponding in number to the plurality of filters for downstream transmission to a subscriber.  
   
   
       7 . The cable network of  claim 6 , wherein the filtered data comprises MAC management messages.  
   
   
       8 . The cable network of  claim 7 , wherein DOCSIS digitized data on the DOCSIS digitized data channel includes MAP data specifying time division multiple access (TDMA) control information for upstream transmission.  
   
   
       9 . The cable network of  claim 8 , wherein the MAP data comprises an 8 bit field for an upstream channel identification.  
   
   
       10 . The cable network of  claim 9 , wherein the 8 bit field is regarded as the most significant bit of a 14 bit service identifier field of the MAP data.  
   
   
       11 . The cable network of  claim 10 , wherein the cable modem termination system transmits up to 256 MAP messages with different upstream channel identifiers.  
   
   
       12 . The cable network of  claim 11  wherein the cable modem of the set-top box uses its own MAP, which is identified by the upstream channel identifier, to transmit upstream bursts of digitized data.  
   
   
       13 . The cable network of  claim 12 , wherein the cable modem termination system uses the logical addressing of the received MAP data and the upstream channel identifier to identify bursts of digitized information from a corresponding set-top box.